Alighting gear



A. P. FAL

ALIGHTING GEAR June M, 1949.

Filed June 12, 1944 I alig i g gear for eration percentage of sand and grit.

have been made to remove i-ce, frost and grit from 5 atentecl June l4, 19 9 2,473,470 I ALIGHTING GEAR Albert P. Fall, Toledo, Ohio Application June 12, 1944, SerialNo. 539,970

2 Claims.

This invention is directed to an improved aircraft or the like andrelates more particularly to an improved packing gland assembiy for such a structure.

My invention has for its principal object the improvements of a retractable alighting gear whereby such a gear is enabled to withstand extreme conditions for a greater number of flying hours than is the case with present structures.

An alighting gear of the type shownherein by way of example, includes an upper sleeve, the upper enclof which may be pivotally attached to the aircraft and a lower rod, to the bottom of which the axle of the wheel is attached. This lower rod telescopes slidingly within the upper sleeve with shock absorbing action. The shock absorbing medium within the sleeve of the strut structure is usually oil or some other satisfactory solution and thus it is necessary that an eflicient seal be established between the lower, inside surface of the sleeve and the outside surface of the rod.

With the packing gland structures utilized in the past, it has been found that considerable difficulty has been experienced when the alighting gear is subjected to extreme conditions brought about by the great distances that present day aircraft travel. The ultimate in a packing gland structure is an assembly which is capable of wiping the rod perfectly clean as it slides within the sleeve to prevent dirt, grit,frost, ice or moisture from serrating or otherwise destroying the gland and also from passing through the gland upwardly into the sleeve.

It is an important object of the present invention to provide an improvedpacking gland assembly which not only affords an efficient seal for the operating liquid but also efficiently removes contaminating moisture, dirt or ice from the rod after is accumulated thereon, this cleaning op.-

taking place during the reciprocationof the rod into the sleeve and being effective upon very thin layers of extraneous, contaminating matter.

One of the contributing factors to the difficulties which are encountered in present packing glands, is the fact that under present conditions a plane may, in a single flight, traverse areas having extreme weather conditions. For instance, a single flight may encounter extremely low temperatures whereupon frost and ice accumulate on the rod and also may traverse desert areas over which the air carries a considerable Previous efi'orts to initiate oil leakage.

It is another object of the present invention to provide an improved packing gland assembly in which the accumulated ice is elficiently removed from the rod so that it will not be forced past the gland to serrate the same and initiate oil leakage.

It is still another object of the present invention to provide an improved packing gland assembly having a sealing gland portion and also having a wiping or scraping portion so constructed as to efficiently cut away ice and frost from the surface of the rod as it reciprocates into the sleeve and to remove grit, moisture and oil from the surface of the rod before the wiped or scraped surface reciprocates through the sealing gland portion.

It is another object of the present invention to provide a wiper-scraper arrangement wherein a wiper annulus is positively pressed against the telescoping rod so that it will not ride over frost, ice or grit particles but will remove the same before the rodsurface slides past a companion sealing gland.

More specifically, it is. an object of the invention to provide, in a packing gland assembly of the above character, a split wiper annulus having an inner cutting edge and an outer compressor carrier groove housing a resilient compressor for urging the cutting edge inwardly against the surface of a telescoping rod to be wiped, the cutting edge thus being positively urged into cutting engagement with extraneous matter on the rod so that it will not ride over the same when the rod slides thereby.

Many other objects and advantages of the invention will become apparent from the following description and accompanying drawings in which:

Figure 1 is a perspective view of a landing strut assembly embodying the features of my invention;

Figure 2 is a cross-sectional view taken on the line II-II of Figure 1;

Figure 3 is an enlarged cross-sectional view taken on the line III-III of Figure 2; and

Figure 4 is a fragmentary enlarged cross-sectional view of the wiper or scraper ring construction showing the manner of its attachment in the assembly.

It is to be understood that the embodiment shown herein is for illustrative purposes only and cation of pressure to engage with external portion '21 in' the usual manner is provided in the upper part "within the lower part may be changed or modified without departing from the spirit and scope of the invention as set forth in the appended claims.

As best shown in Figure 1 the alighting gear shown herein by way of example includes an upper sleeve 10 which serves as a compression cylinder. The upper end of the sleeve or cylinder I is provided with a head II by means of which the entire alighting, assembly may be pivotally secured to the associated aircraft for retraction. Aswill be seen from Figure 2, the lower end of the sleeve ill is open to slidingly receive a rod l2 upon the lower end of which is mounted any suitable axle assemblyl3 for receiving the aircraft wheel.

To the end that the rod l2 ma slidingly reciprocate through the opened lower. end of the sleeve I9 and yet will not rotate therein, a collar 14 having lugs I5 is provided in non rotatable relationship around the lower end of the sleeve 19. Another similar collar I6 having liigs I1 is provided at the lower end of the rod "12, thsecollarsbe'ing connected by a torque link assembly including links [9 and 19 which are "pivoted together as at 29 and are pivoted at "their remote ends respectively to the lugs and IT. 'Thus it will be seen that upon applithe alighting assembly, the 'rod'I'Z will be enabled to reciprocate through the lower end of the sleeve ID, the torque linkage m'ovingto accommodate this reciprocation and at" the same time positively preventing rotation of the rod within the sleeve l9.

" From the foregoing it will be seen that some means must be provided in the mechanism to prevent'leakage of oil and thus loss of operating pressure through the sliding junction of the a lower end of the sleeve or cylinder in and the adjacent portion of the This is accomplished herein by means outside surface of the rod I2. A

of apacking gland'assembly 2! which is cylin drical-"in configuration and is housed within an enlarged portion 22 at the lower end of the sleeve I ll.

The packing assembly is. disposed within the enlarged portion 22 of the sleeve and is compressed therein by a nut 24 having an upwardly extending 'fla'nge'that is internally threaded to threads at'the lower end of T the portion 22- of' the sleeve as shown at 25.

The riut2 l is provided at the lower part thereof with 'a' radially inwardly extending flange 26, the inner edge of which prescribes a adiam'eter somewhat circle having a larger than the outside diameter of the rod 12 which passes therethrough.

"Thus there is provided between the edge of the flange 26 and the rod 12 an annular space available for purposes tobe described'presently.

In order that the packing gland assembly 2| ma carry out its principal purpose; that is the provision of a tight, sliding seal between the sleeve [0 and the rod l2, a compressible sealing made up of a pluralit of segments of the enlarged housing portion 22. The packing' gland assembly is completed by the provision of an annular bearing "member :28 which fits v of the enlarged housing 22 of the sleeve I0 and has an inside diameter of such a size that itsl'idingly receives the rod l2'. This pacln'ng assembly is maintained in the sleeve as shown'in Figure 2 by the attachment of the nut 24 upon the lower end of the sleeve, whereupon the flange 26 thereofis drawn upwardly againstthe'bearing member 28 to'com "the surface of the whee1 rod l2, during retracsurface of the edge 32a press the yieldable gland portion 21 into the position shown.

As indicated previously, one of the major difficulties encountered in the construction and use of telescoping alighting gears, is the entrance of sharp particles such as ice, grit and dirt into the sliding junction between the telescoping parts, whereby the sealing gland is cut and serrated and the outer surf, or grooved so that oilleaka ge -is initiated. This condition then progresses more rapidly since the leaking oil picks up particles of grit whereby, during further reciprocation of the rod, destruction of the seal develops at an increasingly rapid rate. It has also been found that even a slight coating of frost upon the outer surface of the rod l2 serves to produce this undesirable condition and accordingly it is necessary to provide some means which will efficiently remove any contaminating matter whatsoever from the outer rod and leave said surface perfectly clean as it passes through the sealing gland.

To this end there is provided at the lower inside edge of the bearing member 28 a-milled annular groove 29. which is arranged to receive a wiper or scraper assembly. It will be noted that since the groove 29 is positioned at the extreme lower. part of the sleeve ID, the wiper assembly therein, to be described presently, will engage tion thereof, before that portion of the surface so engaged passes along the compressible, 'destructible sealing gland portion '21. Thus". the rod surface is cleaned before it passes the gland and in this manner the introduction of cutting particles or moisture into the glanded junction byretraction of the rod is eliminated.

The wiper assembly shown herein includes a .wiperrscraper annulus 30 which is split as shown at.3l in Figure 3. The wiper .annulus30 includes a radially inner portion 32 which is providedwith a downwardly. projecting rod engaging, cutting edge 32a. and a radially outer portion 33 which seats within thebearing groove 29 and is provided with a compressor groove 34 adapted to receive compressionmeans by virtue of which the annulus3ll and particularly. an edge 32a thereof is compressed resiliently against the outer surface of the rod I2. Any suitable compressor means may be utilized, however, there is shown'herei'n an undulated spring steel annulus 35 havinga depth substantially equal to the compressor groove "34 in the wiper annulus 30, the radially inwardly extending. peaks of which press againstthe inner wall of the groove 34 while the radially outer peaks thereof press against the radially outer wallof the bearing groove 29. Thus it 'will be seen that the compressor annulus 35 urges the entire wiper annulus radially inwardly so that the edge 32a thereof bears inwardlyagainst the outer surface of the rod I2 as the latter isretracted into the sleeve 10. This direction ofthe of the wiper annulus is producedlby a radial outward and upwardinclination of the radially inner surface of the annulus 30 as shown clearly in Figure 4.

The annulus 39 is maintained in the bearing groove 29 by engagement of the radially outer part 33 thereof with the radially innerportionlof the upper surface 'of the flange 26 on thenut 24.

ace of the, rod is worn against the radially outer part 33 of the annulus 30. As indicated previously, the radially inner edge of the flange 26 on the nut 24 is spaced from the outer wall of rod l2 to provide an annular opening. This opening, as will be seen from Figure 4 will be adapted to receive inner, lower cutting edge portion of the annulus 30.

the flange 26 of the nut 24 serves to protect the.

cutting edge 32a of the annulus 30 by virtue of its extension downwardly beyond that edge. In

substantially, vertically centrally of the radiallyouter portion 33 of the annulus 30, this groovemay be disposed in a position vertically upwardly or downwardly of that shown to give different compression characteristics, as desired, dependent upon circumstances encountered in the use of the alighting gear.

From the foregoing it will be seen that there is provided h rein a packing gland assembly which includes a resilient sealing portion and a rod cleaning portion, whereby extraneous matter, accumulated on the surface of the rod will first be removed therefrom by the annulus before the surface of the rod is drawn into contact with the resilient sealing portion of the gland.

Also it will be seen that the wiping annulus 30 and particularly the downwardly and inwardly directed cutting edge 32a thereof will be compressed inwardly by the compressor 35 housed in the groove 34 so that the cutting edge will not ride over extraneous matter on the surface of the rod l2. Instead, the edge 32a will be urged inwardly in a cutting direction.

Preferably the annulus 30, when associated with the rod I2, is slightly spread to permit inward compression thereof against the rod by compressor 35. This insures the proper amount of pressure of the cutting edge 32a against thetight fit of the annulus: to the rod if the latter is slightly out of round or rod and also affords a slightly off size.

I claim as my invention:

1. In a packing gland for disposition at the junction between the telescoping members of an alighting gear or the like in which a piston rod reciprocates with respect to a cylinder and in the radially With this construction it will be seen that 1 which a bearing member is disposed in the cylinder about the piston adjacent said junction with the bearing formed with an annular groove, that improvement which comprises a one-piece split metal wiping or scraping ring disposed in said bearing groove, said ring having at the radially inner part thereof a cutting edge against the piston surface and having in its convex peripheral portion a compressor groove, and a compressor in said compressor groove between it and the said bearing groove acting with squeeze grip action about the ring tending to compress the ring and reduce the diameter of its cutting edge and thus increase the contact of the cutting edge against the piston.

2. In a packing gland for disposition at the junction between the telescoping members of an alighting gear or the like in which a piston rod ,reciprocates with respect to a cylinder and in which a bearing member is disposed in the cylinder about the piston adjacent said junction with the bearing formed with an annular groove, that improvement which comprises a one-piece split metal wiping and scraping ring disposed in said bearing groove, said ring having at the radially inner part thereof a cutting edge against the piston surface and having in its convex peripheral portion a compression groove coextensive with the circumferential extent of the ring, and acne-piece split sinusoidal spring in said groove having the apices of one side surface in bearing engagement with the concentric surface of the bearing groove and the apices of the other side surface of the spring against the bottom of the ring groove to thereby exert wedging action about the ring to squeeze press the cutting edge thereof into tight engagement with the piston surface. ALBERT P. FALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,497,125 Sorrells June 10, 1924 -1,594,935 Force Aug. 3, 1926 1,822,521 Fox et a1 Sept. 8, 1931 1,837,115 Cook Dec. 15, 1931 1,900,437 Durham Mar. 7, 1933 1,992,746 Fortune Feb. 26, 1935 2,197,474 Johnson Apr. 16, 1940 2,290,507 Thompson July 21, 1942 

